Radio tuner



Augo 16 1949. c, JONES 2,478,925

RADIO TUNER Filed Oct. 1, 1945 z z/a/m'm/z PETEE a. JON/f5 BY 5 2U d AM:

Patented Aug. 16, 1949 UNITED STATES PATENT OFFICE 2,478,925 iiAiiio TUNER Peter 6. Jones, Dayton, Ohio Animation October 1, 1945, Serial Not 619;?21 scares (01.171-119) (Granted imder the act or March 3, 1883, as

The invention described herein may be m nufactured and used by or for tfie Gove' inent for governmental purposes without payment to me of any royalty thereon.

This invention relates to radio tuning and has particular reference to a tuning dvioe for all wave radios. V I g An obj eot of the invention is to provide a t'i'ln ing device which combines the functionsof a coil and a variable conden's''r; tame end that both space and material will conserved. v X 7 Another object is to provide tuni g device which is adaotable' to a linear tuning dial without strings and pulleys for spare-ting the frequency indicating pointer.

Another object is u; prtvide' t which a greater rainge of v i with those of conventionalesign. j g H Further objects and advan ages will be evident from a consideration of the roiiewisg' aesenpnon, taken in conjunction with the" drawings, where Fig. 1 is a perspective view of the tun-er V Fig. 2 is a longitudinal section through the guide rods and coils. A n

Lik'e're'ierence characters refer to like parts throughout the several views; 4

Referring now to the awing's; the tubular guide rods I are press-fitted at tli ends into end heads I2 which constitutes s f m'e'vvork for the device. Pins l4 may be uses to further secure the guide rods in the head's;

A carriage i8 is 'slidable lo itu'tiir'ially on the guide rods and is propelled theralong by arack and pinion movement, the rack l8 of which may preferably be set in notches in the heads 12 and fastened by screws 20, and the pinion 22 01 which may have its rotative bearing on a shaft 24 (see Fig. 2) which extends transversely through the carriage I6. A knurled thumb and finger knob 26 is provided for rotating the pinion, which may preferably be provided with -s'o'me form of anti backlash means, the means shown being" well known in the art and consisting of making the gear in two layers, each layer with e timate slot 2?, and placing a small oil spring 2'9 in the slots with one end of the spring reacting against the end of the slot of one layer and the other end of the spring reacting against the opposite end of the slot of the other layer. I

Tapped mounting holes 28 are provided in the heads l2 for securing the device in a radio cabinet, slots in the face of the cabinet (not shown) being provided for the knob 26 and for a pointer 30 which is fast on the carriage l6 and may amended April 30; 1928; 370 0; G. 757) 2 reach through the slot provided for it and co operate with a linear dial on the face or the cabinet to indicate the frequency setting. Inductance an' be plOtted in terms of physical movement of the pointer 30 by the carriage 16.

The arrangement shown may preferably be used for the reason that it provides a maximum of linear adjustment in minimum space. The alternative,- however, of securing the rack l8 to the carriage l5, and providing rotative bearingfor the-shaft 24 in one of the heads 12; is con sidered to be within the scope of the invention. So also, a roller may be placed on the carriage [6 under the lower edge of the rack [3 whereupon the rack need not be supported on the right-hand end head and this headmay be eliminated if desired.-

A single-layer primary coil 32 Fig. 2,- is shown as being Wound directly on the guide rod [9; the coil beginning at the binding screw 34, andex tending through a longitudinal groove in the rod 10 to the opposite end, then being wound on the outside of the tube and ending at the terminal screw 36. A thin noncon'duc'tive cover 38 is shown as surrounding the primary coil 32.

Although shown in a fixed position, the primary coil may be made movable in increments controlled by the carriage I6. This method will control the c'o'efiicient of coupling between the primary and secondary and conceivably the C0 efficient of coupling may be kept constant over the entire frequency range of the device.- More over, it is to be understood that in this device the change of frequency may" be made a linear function;

A single-layer secondary coil 40' is formed from a length of strip stock about .011 thick and soprdximately .125" Wide Wdufid ed'g'wis'e into the form of a clos'edcoil spring; the first and last turns being connected to the binding screws 42 and 44 respectively. Parts 32 through 44 when assembled may be broadly designated by the numeral 46.

The Oscillator (foil 48 is in every respect like the coil 46 except that it is shorter, a hub 50 being provided on the carnage IE" to take up the difference in length. Slugs 52 and 54 of compressed powdered iron are fixed in the ends of the guide rods l0 within the coils 46 and 48 respectively.

The operation of the device is substantially as follows:

When the tuning knob 26 is turned clockwise, the carriage l6 moves from the extreme left position shown to the right, and stretches out the game secondary coils 40 and 40a thereby lengthening the flux path and coincidentally increasing the space between the flat sides of the coils, whereby the normal inductive and capacitative reactance are decreased simultaneously thereby increasing the frequency. Because of the slugs 52 and 5d, the ratio of lowest to highest frequency is increased. Moreover, since the capacitance is increased or decreased in the coil itself, no other variable condenser is required.

While I have shown and described a tunin device having an oscillator coil in the set it will of course be understood that in situations where this coil is not needed it may be omitted. 7

Having described an embodiment of my invention, I claim:

1. A radio tuning device which comprises, in combination, a hollow guide rod, an end head at each end of said hollow guide rod, a rack supported at its ends on said end heads, a carriage slidable on said hollow guide rod intermediate said end heads, an anti-backlash pinion in mesh with said rack, a shaft for said pinion having rotative bearing in said carriage, a thumb and finger knob associated with said shaft and pinion for rotating said pinion, a primary coil wound on a part of said rod adjacent one end head and fixed against endwis-e movement on said hollow guide rod, the beginning and end of said primary coil being attached to said one end head, a secondary coil freely surrounding said primary, coil and having one end attached to said one end head and the other end secured to said carriage, said secondary coil being composed of relatively thin but wide strip of conductive material wound edgewise, whereby movement of said carriage away from the end of said primary coil lengthens said secondary ,coil, thereby increasing the distance between the turns of said secondary coil, and a slug of compressed powdered magnetic material positioned within the hollow of said guide rod within the length of said primary coil.

2. A radio tuning device which comprises, in combination, a guide rod, an end head fast on the end of said guide rod, a rack supported at its end on said end head, a carriage slidable on said guide rod, a pinion in mesh with said rack, a shaft for said pinion having rotativebearing in said carriage, a knob associated with said shaft and pinion for rotating said pinion, a primary coil wound on a part of said rod adjacent the end head and fixed against endwise movement on said rod, the beginning and end of said primary coil being attached to said end head, a secondary coil freely surrounding said primary coil and having one end attached to said end head and the other end secured to said carriage, said secondary coil being composed of relatively thin but wide strip of conductive material wound edgewise, whereby movement of said carriage away from the end of said primary coil lengthens said secondary coil, thereby increasing the distance between the turns of said secondary coil, and a magnetizable core positioned in said guide within the length of said primary coil.

3. A radio tuning device which comprises, in

4 combination, a guide, a head at the end of said guide, a rack supported at its end on said head, a carriage slidable on said guide, a pinion in mesh with said rack, means for providing rotative bearing for said pinion in said carriage, a knob associated with said pinion for rotating said pinion, a primary coil wound at one end of said guide adjacent the end head and fixed against endwise movement with respect to said guide, the beginning and end of said primary coil being attached to said head, and a secondary coil freely surrounding said primary coil and having one end attached to said head and the other end secured to said carriage, said secondary coil being composed of relatively thin but wide strip of conductive material wound edgewise whereby movement of said carriage away from the end of said primary coil lengthens said secondary coil thereby increasing the distance between the turns of said secondary coil.

4. A radio tuning device which comprises, in combination, a guide, a carriage slidable on said guide, means to slide said carriage along said guide, a primary coil wound on said guide adjacent one end and fixed against endwise movement thereon, and a secondary coil freely surrounding said primary coil and having one end fixed with respect to said guide and the other end secured to said carriage, said secondary coil being composed of relatively thin but wide strip of conductive material wound edgewise, whereby movement of said carriage away from the end of said primary coil lengthens said secondary coil thereby increasing the distance between the turns of said secondary coil.

5. A radio tuning-device which comprises a primary coil of fixed length, a secondary coil having one end fixed with respect to the primary coil and the other end-movable axially, said secondary coil being composed of close-up turns of a relatively wide but thin strip of electrically conductive material wound edgewise, and means to stretch the turns of the secondary coil apart whereby the inductance and capacitance is simultaneously decreased.

6. A radio tuning device which comprises a primary and a secondary coil, said secondary coil being composed of turns of a relatively wide but thin strip of electrically conductive material coiled edgewise, and means to progressively change the relation between the axial lengtth of the secondary and the axial length of the primary, whereby the inductance and capacitance is simultaneously altered.

PETER C. JONES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 793,777 Fessenden July 4, 1905 848,676 Murgas Apr. 2, 1907 1,533,749 Meirowsky Apr. 14, 1925 2,238,763 Winkler Apr. 15, 1941 

